This invention relates to self-mating reclosable mechanical fasteners, which have structural elements that project from a base sheet and interengage with the structural elements of an identical fastener to thereby connect the fasteners together, as well as connect together articles on which the fasteners have been mounted.
Hook-and-loop fasteners (as taught, for example, in U.S. Pat. Nos. 2,717,437 and 3,009,235) are in common, everyday use; but they still have important deficiencies:
the hooks can be rough against bare skin;
the hooks can snag fabrics or other materials that are not intended to be target substrates;
the hooks can collect lint, especially during laundry cycles;
the hook-and-loop composite is a relatively thick laminate, and can be conspicuous, e.g., in clothing applications;
loop material, especially in robust constructions, can be relatively costly;
opening or unfastening hook-and-loop fasteners can cause detachment of loops from their substrates, with a consequent generation of particulate debris; and
the potential for particulate debris in hook-and-loop fasteners precludes their use in clean room environments and other areas where debris is destructive.
A wide variety of different fasteners have been taught as alternatives or replacements for hook-and-loop fasteners, including molded and extruded articles from which headed, interengaging elements protrude. See, for example, the fasteners described in U.S. Pat. Nos. 3,266,113; 4,290,174; 4,894,060; and 5,119,531. Many of these fasteners are self-mating, i.e., fastening is accomplished by interengaging fastener units of identical shape.
Despite the many alternative fasteners taught in the prior art, a need still exists for improved fasteners, having new combinations of properties that adapt the fastener for improved performance in existing and new applications. And the improved fastener performance often must be achieved with constructions and processes that give the fasteners a very low manufacturing cost, especially for certain applications such as use on disposable garments or other articles.
The present invention provides a new self-mating fastener, which comprises a base sheet and a multiplicity of parallel, narrowly spaced, elastically deformable ribs projecting from a major surface of the base sheet. The ribs comprise a stem portion, which is attached to and is substantially upright from the base sheet, and at least one flange attached to each side of the stem portion at points spaced above the base sheet. At least the outer portions of the flanges desirably project downwardly toward the base sheet. The cross-sectional profile of the fastener formed by the ribs is substantially uniform over the length of the ribs; but the profile has a repeated deviation in the direction transverse to the ribs from the profile that would be formed by a full population of identical, equally spaced, undivided, symmetric ribs. The width and spacing of ribs are chosen so that when the ribbed surface of the fastener is pressed against an identical ribbed surface, the ribs of one surface will be accommodated between the ribs of the other surface, and ribs on the two surfaces can deform and their flanges move past one another to interengage and hold the surfaces together.
Fasteners as described have a number of important advantages, as will be discussed in the detailed discussion that follows. These include convenient engagement at a desired level of pressure or force; resistance to disengagement, especially resistance to peel forces, which combines with low engagement force to provide a wide range of utilities; an advantageous self alignment when fasteners are brought into engagement with one another; high durability adapting the fasteners to repeated use; low manufacturing cost; and low inventory cost, given the need to stock only one product in the case of a self-mating fastener.